Interpretive Summary: Intraruminal infusion of oligofructose alters ruminal microbiota and induces acute laminitis in sheep.
By: Surely Wallace
In a December 2017 article published in the Journal of Animal Science, researchers induced acute laminitis in sheep with oligofructose. Oligofructose has been previouslyshown to induce laminitis in cows and horses; the authors hypothesized it would have the same effect on sheep. The purpose of this study was to develop a sheep model to study laminitis, and to also determine potential inflammatory or microbial contributory factors in laminitis.
Laminitis is a debilitating inflammatory disease affecting the connective tissue and hoof. Its etiology is unclear, but poor blood flow is hypothesized as causal. Excessive fermentable dietary carbohydrate (carbohydrate overload) is also a potential contributing factor. The study’s authors suspected inflammation and changes to rumen microbiota in response to carbohydrate overload would be contributory to laminitis in sheep.
The study included 10 healthy male sheep of similar body weight and age (5 control, 5 treatment) fitted with a cannula port for easy rumen access. The experimental period lasted 36 days. Sheep were fed a normal diet for 30 days, followed by 3 days of oligofructose infused into the rumen (21 g/kg of body weight) in the treatment group. All animals were observed for clinical symptoms and sacrificed at the end of the experimental period. Rumen microbiota, inflammatory factors, and laminal tissue histology were studied.
Oligofructose treated sheep developed diarrhea, anorexia, roach back and lameness. No sheep from the control group had laminitis symptoms. Histological evaluation of laminal tissue confirmed clinical observations. In the sampled rumen contents, lactate increased, and pH and total volatile fatty acids (VFA) decreased in the treatment group. Rumen microbiota also changed significantly. In the treatment group, Firmicutes were more abundant (80.43% vs. 50.57%) due to increases in Streptococcus and Lactobacillus, whereas Bacteroidetes were less abundant (43.57% reduced to 14.41%). Increased expression of pro-inflammatory molecules (IL-6 and metalloprotease-9) were also found in laminal tissue in the treatment group. The authors postulated that carbohydrate overload from oligofructose may have caused lactic acid producing Firmicutes to proliferate, decreasing pH of the rumen, leading to rumen acidosis and inflammation. Rumen acidosis has been shown in previous studies to potentially contribute to laminitis.
Overall, this study proposes a sheep model for studying laminitis. It also provides valuable data on the potential connection between rumen microbiota and laminitis. Although larger and more in-depth studies are needed, this small study suggests there may be a potential relationship between changes to rumen microbiota in response to carbohydrate overload, and the development of laminitis in sheep. The authors noted rumen microbial changes and reduced rumen pH in sheep treated with oligofructose was concurrent with laminitis.
To view the full article, “Intraruminal infusion of oligofructose alters ruminal microbiota and induces acute laminitis in sheep,” visit Journal of Animal Science.